The pattern of arrangement of leaves on the stem or branch is called phyllotaxy. It helps to avoid overcrowding and provides every leaf with optimum sunshine.
Phyllotaxy is usually of three types:-
 ALTERNATE PHYLLOTAXY
A single leaf arises at each node in an alternate manner.
Examples are China rose, Mustard and Sunflower
 OPPOSITE PHYLLOTAXY
A pair of leaves arise at each node and are opposite to each other.
Examples are Calotropis and Guava
 WHORLED PHYLLOTAXY
If more than two leaves arise at a node and form a whorl, it is called whorled. The leaves of one whorl is generally alternate with those of the adjacent whorls in order to provide maximum exposure.
Examples are Nerium (Kaner), and Alstonia